The intestinal intraepithelial lymphocytes with T cell receptor αβ express toll-like receptor 4 and are responsive to lipopollysaccharide

Background: Intestinal intraepithelial lymphocytes (iIELs) play an important role in intestinal innate immunity and oral immune tolerance. To compare the differences in gene expression between murine iIELs and splenic T lymphocytes, we established the cDNA subtractive library of iIELs and analyzed the iIELs special genes. Our study focused on the relationship between Toll-like receptor 4 (TLR4), TLR5 and ilELs. Methods: Ninety percent purified iIELs and splenic T lymphocytes were isolated by density-gradient centrifugation in a Percoll and nylon column, respectively. We then established the cDNA subtractive library of iIELs via improved subtractive hybridization. The special expressed sequence tags of iIELs were screened by reverse Northern blot. The expressions of TLR4 and TLR5 were analyzed by RT-PCR and fluorescence staining. The proliferation of T cells was determined by H-3-TdR incorporation. Results: TLR4, but not TLR5, was detected in iIELs by RT-PCR and fluorescence staining. However, TLR4 was only found in alpha beta ilELs. Furthermore, iIELs were observed to proliferate in response to lipopolysaccharide in vitro, with upregulation of IRAK-1 mRNA expression. Conclusion: alpha beta ilELs can recognize lipopolysaccharide via TLR4, which may play an important role in the intestinal innate immunity. Copyright (c) 2006 S. Karger AG, Basel.